chem paper 22 KC expression

[Balaj Hassan]

Guys can u please tell me what was the expression for kc??? in chem paper 22 AS level.
Thank you.

 

[aliester]

ya please some1 tell me too!

 

[olenka1611]

i dont knw how but out teacher said it was 0.44!) with no units..!) i dnt think a teacher cud be completely wrong?

 

[hassam]

really......a teacher said..........r u sure..though i believed i did rong bt u givin me renewed hope

 

[Balaj Hassan]

lemme tell you no chance 0.44 could be answer but if u guys ask i can give u fully detailed explanation.

 

[aliester]

do tell.

 

[Balaj Hassan]

hmmm we all know that 0.045 moles of NaOH were used??? and 0.005 reacted with HCl so what remained were 0.04 moles of NaOH. but the thing is they told us in the question that this sample was taken when equilibrium was established kk??? so it means that at eqm 0.04 moles of ethanoic acid were present. now start putting the moles the starting moles are 0.1 mole of ethanoic acid at eqm it is 0.04 mole so it means that 0.06 moles reacted. so now just apply kc expression which will be 0.6 squared as ester and water are there DIVIDED by 0.4 squared of both alcohol and ethanoic acid and u get 2.25 as the answer. Hope u got it but if u still have doubt do ask.

 

[Sannikutti]

exactly balaj hassan is right
My dear friends
This is How it goes;
After equilibrium which is reached NaoH which was 0.045 was titrated which was against HCL And Organic acid
Now that 0.005 is reacted with catalyst,so how much NaOH reacted with rest of organic acid which is 0.040 ok so if 0.1 mole of oraganic acid was there befor the equilibrium
and there was also 0.1 moll of that alcohol what happens is tht theyll reach equilibrium and then what happens is tht what ever was gone into the equilibrium was
0.1-x which x denotes the amount of acid which is there in equilibria
so if after equilibrium 0.04 of NaOH was there tht means 0.04 moles of the acid was remaining at equilibrium which was not gone into product making
so tht means tht 0.1-0.04=0.06
so 0.06 mole is gone into the equilibrium
so if 0.06 of acid react with 0.06 of alcohol
so 0.06 of easter and H20 are made respectively
so it will be 2.25 with no units
and i saw a post previously which said tht about making easter which was glycerol and the acid i dont remember what was the acid
it reacts 1 is to 1
which means that ooh react with oh to produce water and easter
so onlyone -OH group will go and rest is same
so the easter will be CH3-(CH2)16-coo-ch2-choh-ch2oh
hpe tht it cleares all the doubt

 

[Balaj Hassan]

sanni can u plz clear to me about the expression if we say that equation is hetero genous so we have to omit water or not???

 

[Sannikutti]

what heterogenius when it was given
if it is hetero then water is omited
but this reaction which is what we did in chem
was not hetero was homo
cuz all the reactants and products were in liquid states
proof is
http://en.wikipedia.org/wiki/Homogeneit ... erogeneity
hope it helps
Salam alaikum warahmatullah wa barakatuhu